1. Field
The invention relates to wireless communications. More particularly, the invention relates to methods and apparatus for using a licensed spectrum to transmit a signal when an unlicensed spectrum is congested.
2. Background
Wireless communications continues to grow in demand and has become an integral part of both personal and business communications. Wireless communications allow users to transmit and receive data from most anywhere using wireless networks and wireless devices such as laptops, cellular devices, iPhones, BlackBerrys, etc.
Wireless devices are generally configured to operate in either a licensed frequency spectrum or an unlicensed frequency spectrum. Different countries have set aside different portions of the frequency spectrum as the licensed frequency spectrum and the unlicensed frequency spectrum for operation of wireless devices. As an example, in the United States, the 1.9 GHz spectrum has been used as a licensed spectrum for broadband wireless devices. Outside the United States, the 3.5 GHz spectrum has been the most widely used licensed spectrum for broadband wireless devices. The licensed spectrum includes all frequency bands that require a license to operate a wireless device. In the licensed spectrum, only the spectrum licensee can build infrastructure, and allow communications and offer services across its spectrum range. The licensed spectrum is more reliable and has less traffic congestion but generally has a narrower bandwidth when compared to the unlicensed spectrum. Hence, large amounts of data may take longer to transmit using the licensed spectrum.
The unlicensed spectrum includes all frequency bands that do not require a license to operate a wireless device. In the unlicensed spectrum, any user is free to use the frequency band for short range wireless communications. The unlicensed spectrum is inexpensive and has a larger band when compared to the licensed spectrum but is not controlled by any third party so can be unreliable and congested due to large amounts of data passing across these frequency bands. However, when the unlicensed spectrum is not congested, it can be useful for transferring large amount of data.
In the United States, the unlicensed spectrums are at 2.4 GHz and at 5.2 GHz, of which are both free to use. The Federal Communications Commission (FCC) currently sets requirements for the unlicensed spectrums such as limits on transmit power spectral density and limits on antenna gain.
Therefore, it has been recognized by those skilled in the art that a need exists for methods and apparatus for using a licensed spectrum to transmit a signal when an unlicensed spectrum is congested.